diff --git a/tests/cputest.c b/tests/cputest.c
index 36bac9b..1368cd3 100644
--- a/tests/cputest.c
+++ b/tests/cputest.c
@@ -40,7 +40,10 @@
 #include "msp430setup.h"
 #include <stdio.h>
 #include <string.h>
-#if __MSPGCC__
+#if defined(__GNUC__) && (__GNUC__ >= 9)
+#include <msp430.h>
+#include <stdarg.h>
+#elif __MSPGCC__
 #include <msp430.h>
 #include <legacymsp430.h>
 #define eint() __eint()
@@ -79,7 +82,7 @@ static int caseID = 0;
 /*---------------------------------------------------------------------------*/
 static int pos = 0;
 static unsigned int times[10];
-interrupt(TIMERB1_VECTOR) timerb1 (void)
+ISR(TIMERB1, timerb1)
 {
   if(TBIV == 2) {
     if(pos < 10) {
@@ -266,7 +269,7 @@ static void testBitFields() {
 
 /*--------------------------------------------------------------------------*/
 static int flag;
-interrupt(UART0TX_VECTOR) usart_tx_test0 (void)
+ISR(USART0TX, usart_tx_test0)
 {
   printf("*IRQ: Flags:%d %d\n", IFG1, UTCTL0);
   flag++;
diff --git a/tests/msp430setup.c b/tests/msp430setup.c
index 9012f9c..d13e91c 100644
--- a/tests/msp430setup.c
+++ b/tests/msp430setup.c
@@ -37,7 +37,9 @@
  */
 
 #include "msp430setup.h"
-#if __MSPGCC__
+#if defined(__GNUC__) && (__GNUC__ >= 9)
+#include <msp430.h>
+#elif __MSPGCC__
 #include <msp430.h>
 #include <msp430libc.h>
 #include <legacymsp430.h>
@@ -49,7 +51,6 @@
 #endif /* __MSPGCC__ */
 #include <stdio.h>
 
-
 /*--------------------------------------------------------------------------*/
 /* RS232 Interface */
 /*--------------------------------------------------------------------------*/
@@ -57,8 +58,7 @@
 static int (* input_handler)(unsigned char) = NULL;
 
 /*---------------------------------------------------------------------------*/
-interrupt(UART1RX_VECTOR)
-     rs232_rx_usart1(void)
+ISR(USART1RX, rs232_rx_usart1)
 {
   /* Check status register for receive errors. - before reading RXBUF since
      it clears the error and interrupt flags */
@@ -129,12 +129,24 @@ rs232_set_input(int (*f)(unsigned char))
   input_handler = f;
 }
 /*--------------------------------------------------------------------------*/
+#if defined(__GNUC__) && (__GNUC__ >= 9)
+int
+write(int fd, const char *buf, int len)
+{
+  int i = 0;
+  for(; i < len && buf[i]; i++) {
+    rs232_send(buf[i]);
+  }
+  return i;
+}
+#else
 int
 putchar(int c)
 {
   rs232_send(c);
   return c;
 }
+#endif
 /*--------------------------------------------------------------------------*/
 
 
diff --git a/tests/msp430setup.h b/tests/msp430setup.h
index 939507b..7a94fa7 100644
--- a/tests/msp430setup.h
+++ b/tests/msp430setup.h
@@ -39,6 +39,15 @@
 #ifndef __MSP430SETUP_H__
 #define __MSP430SETUP_H__
 
+#if defined(__GNUC__) && (__GNUC__ >= 9)
+#define ISR(a,b) void __attribute__((interrupt(a ## _VECTOR))) b(void)
+#define eint() __eint()
+#define dint() __dint()
+#elif defined(__GNUC__)  &&  defined(__MSP430__)
+     /* This is the MSPGCC compiler */
+#define ISR(a,b) interrupt(a ## _VECTOR) b(void)
+#endif
+
 void msp430_setup(void);
 
 #define RS232_19200 1
diff --git a/tests/timertest.c b/tests/timertest.c
index 12d6b20..f266197 100644
--- a/tests/timertest.c
+++ b/tests/timertest.c
@@ -38,7 +38,9 @@
  */
 
 #include "msp430setup.h"
-#if __MSPGCC__
+#if defined(__GNUC__) && (__GNUC__ >= 9)
+#include <msp430.h>
+#elif __MSPGCC__
 #include <msp430.h>
 #include <legacymsp430.h>
 #else /* __MSPGCC__ */
@@ -80,7 +82,7 @@ static volatile unsigned int count = 0;
 static volatile unsigned int seconds = 0;
 static volatile unsigned int last_tar = 0;
 
-interrupt(TIMERA1_VECTOR) timera1 (void)
+ISR(TIMERA1, timera1)
 {
   if(TAIV == 2) {
     eint();
@@ -104,7 +106,7 @@ interrupt(TIMERA1_VECTOR) timera1 (void)
 
 
 /*---------------------------------------------------------------------------*/
-interrupt(TIMERA0_VECTOR) timera0 (void)
+ISR(TIMERA0, timera0)
 {
   ticka0++;
   TACCR0 += 4;